With the potential downsides of conventional fossil fuel and nuclear power sources well known, ongoing efforts are being made to practically and economically exploit clean, renewable power sources. The energy latent in the movement of water, or hydro-kinetic energy, was one of humankind's earliest power sources and is increasingly being looked to again for clean, renewable power.
Where there is a consistent and rapid flow of water, generating hydro-kinetic power is relatively easy. For example, many hydroelectric plants have been established in connection with dams along rivers. Unfortunately, the environmental impact of damming a river can be quite high. Limited efforts have been made to place turbines directly on riverbeds, to allow river power to be harnessed without the major environmental impact of a dam. However, such turbine systems still require the presence of a suitable river.
Harnessing tidal energy is another approach being explored, and to some degree, exploited. While tidal energy is theoretically available along all ocean coastlines, tidal flow characteristics vary greatly from place to place. Additionally, the approximately 12 hour tidal cycle does not lend itself to continuous power generation at a given location. Instead, recurring periods of virtually no tidal flow will alternate with long periods of increasing and decreasing flow.
Although wave magnitude can vary greatly between coastal locations, some appreciable wave action is likely to be present along virtually all ocean coastlines. Additionally, larger lakes and seas can experience significant wave action. However, most wave power systems being tested tend to focus on surface waves. While wave magnitude is generally greatest at the surface, it is also more prone to significant fluctuations with changes in wind conditions. These fluctuations can more readily result in damage to, or loss of, power generating equipment. Also, at least some components of the power generating equipment must be at or very near the surface, where such components can present a hazard to navigation.
Subsurface wave action at relatively shallow depths underwater (approximately 30-80 feet), while correlating to surface wave activity, tends to be much more regular. Accordingly, subsurface wave action represents a potentially widespread and consistently-utilizable source of clean, renewable power. Attempts have been made to utilize subsurface wave action for power generation, including the development of systems with pivotably mounted wings that move back and forth with the wave action; however, further improvements are possible.